I picked this game up because it was on sale for 50% off and I realized that I had not played a RTS in ages. 50+ in game hours later, and I'm still hooked. Definitely worth every cent I spent on it.
As other have said, the game plays like a cross between Settlers, Age of Empires and Civilization, and it is a lot of fun. It's fairly easy to learn, but can be devilishly hard to master. There are many aspects to one's economy, never enough workers, and everything is a valuable resource - food to feed your clan, wood to build more buildings, stone to upgrade them, iron to improve your workers and warriors, gold to pay for just about anything, lore to learn new abilities, even happiness, which decides how quickly your clan grows. Mix in the fact that the map is divided into tiles, which have to be colonized (and often conquered) first, and most of them are unique in what type of and how many buildings they can support, and you can have some pretty hard to choices to make...
And on top of everything, there's the neutral factions that will regularly invade your territory (kobold, draugr, or even just wolves), and the other players who don't exactly have your best interests at heart either, so you'd better not just focus on having a healthy economy but also a strong enough warband to defend and expand your territory with...
All in all, a great gem of a game that rekindled my love for the whole RTS genre.